Machine for and method of cutting undercut cutters



7 SHEETS-SHEET 1 F. M'JLLER. Mmm-HN: Fon me Msn-lon oF Cur'rmc LNoERcuT flu-runas FoLeo MAY I3. [92h Jan. 3o, 1923.

Jan. 30, 1923.

F. MULLER. MAcHmE Fon AND MErHoo oF CUTTING UNDERcur Cu'r'rERs 7 SHEETS-SHEET 2 FaLEo Mu 13* |92, i

Jan. 3o, 1923. I,

F MULLER MACH r NE FOR ANO METHOD oF CUTT NG UNDERCUT CUYTERS F4 LED MAY 13, I 92| 7 SHEETS-SHEET 3 Jan. 30, 1923. 1,443,638

Fl MULLER` MACHJNE Fon AND METHOD oF Currms UNDERCUT CUTTER.;`

FILED MAv 13. |921. 7 SHEETS-SHEET 4 E .i l

Jan. 30, 1923. 1,443,638

F MULLER MAcHsNE Fon AND METHOD 0F CuTTlNs UNDERCUT CUTTERS Fl LEO MAY I3, 92|

7 SHEETS-SHEET 5 l l 1 l moi/neg Jan. 30, 1923.

F. MULLER. MACHINE FOR AND MEYHoD oF CUTTING UNDERcujr CuTTERs,

7 SHEETS-SHEET 6 FILED MAY 13,'92l.

F MULLER 4 MACH Ns Fon AND METHOD oF CUTT NG UNDERcuT CUTrr-:Rs

Jan. 30, 1923.

7 SHEETS-SHEET 7 Fr LED MAY I3. i921 Snom/tez www @www abbaia/wig.

Patented an. 30, 1923.

UNITED STATES PATENT OFFICE.

FRIEDERICH MLLER, OF HARTFORD, CONNECTICUT, ASSIGNOR T0 PRATT d', WHIT- NEY COMPANY, OF NEW YORK, N. Y., A

CORPORATION OF NEW JERSEY.

MACHINE FOR AND METHOD OF CUTTING UNDERCUT CUTTEBS.

Application filed May 13, 1921. Serial No. 469,266.

To all whom t may concern.'

Be it known that I, FRIEDERICH MLLER, a citizen of the United States residing at Hartford, in the county of artford and State of Connecticut, have invented certain new and useful Improvements in Machines for and Methods of Cutting Undercut Cutters, of which the following is a specification.

My invention relates to relieving machines for operating on cutter blanks having teeth provided with non-radiall arranged cutting faces fand to metho s of shaping cutterblanks having non-radially arranged cuttin faces.

One object o 'my invention is to provide a machine that shall cut a blank to a rectilinear or to a nonrectilinear contour` while relieving the teeth and'compensating such relieving operation at different blank diameters for nonradially arranged cuttin faces on the teeth of the blank.

nother object of my invention is to provide a relieving machine that shall cut a blank, vwhich is provided with helical teeth having undercut or non-radially arranged cutting faces, to a predetermine rectilinear or non-rectilinear contour while relieving the helical teeth on the blank and compensating such relievin operation for the non-radially arrange cutting faces on the teeth of the blank.

Another object of my invention is to provide a machine of the above indicated character that shall be provided with a pin and a former for guiding a cutting tool to cut the blank to a predetermined contour, means for relieving the teeth of the blank in conformity either to helical or straight teeth, and means for so varying the relieving operation as to compensate at different blank diameters for non-radially arranged cutting faces on the teeth of the blank.

Another object of my invention is to provide means for varying the rotative movement of the spindle, which carries the metal blank, in accordance with the helical teeth on the blank in combination with means for relieving the teeth, and means for vary ing the relieving operation at different blank diameters to compensate for the nonradial cutting faces on the teeth of the lank.

.Another object of my invention is to provide a relieving machine with lmechanism for effecting intermittent longitudinal feeding movements between the cutting tool and the blank, means for stop ing the blank rotation during each fee ing movement, means for effectin transverse movements of the tool to permlt the intermittent longitudinal feeding4 movements, and means `for relieving the teeth of the blank While compensating at different blank diameters for the non-radial cutting faces on the teeth.

Another object of my invention is to provide a'method that shall form a blank with a rectilinear or a non-rectilinear contour while relieving the teeth and compensation' such relieving operation at different blan diameters for non-radially arranged cuttin faces on the teeth of the blank. 4

nother object of my invention is to provide a method of forming a milling cutter which consists in effecting intermittent longitudinal feeding movements between a cuttino tool and the cutter blank, in stopping tie blank rotation during each feeding movement, in effecting transverse `movements of the tool to permit the intemittent longitudinal feedin movements, `and in relieving the teetho? the blankV while effecting compensation at different blank diametcrs for the non-radial cutting faces on the teeth.

A further object of my invention is to provide a relieving machlnefwhich elfects feeding movements of the above indicated character, that shall be provided with means, preferably comprising a pin and a former, for so guiding a cutting tool as to cut the blank to an predetermined variable contour while e ecting relieving Inove` ments and that shall compensate the relieving operation at diii'erent blank diameters for non-radial cutting faces on the teeth of the blank.

More specifically, my invention comprises a relieving machine for cutting a blank, which is provided with either helical or straight teeth having undercut or nonradially arranged cutting faces, to any predetermined contour w ile relieving the teeth of the blank and, moreover, While varying either the relieving movements or the position of the relievin movements to compensate at different blan diameters for the teeth are helical in clined in either direction with variations in radius at different points along the non-radially arranged cutting faces on face. Preferably, the relief lines are mainthe teeth of the blank. tained in similar relationship to each other In the art of cutting many materials and as they extend backward and inward, the particularly in cutting metals, it is preflines conforming to spirals of Archimedes. erable for many classes of work to incline When the relief lines conform to spirals the face of the cutting tool backward with and are maintained in similar relationship respect to the direction ofmovement thus as they extend backward and inward, as is providing a rake or undercut which propreferred, it is possible to sharpen or grind vides a sharper cutting edge and enables the teeth of the cutter on the front cutting other advantages to be obtained. To a very faces without changing the effective conlimited extent this principle has been aptour. The teeth present the same effective plied to millin cutters, the cutter faces becontour at successive nonradial helicoidal 1n inclined ackward with respect to surfaces of intersection similar in form and radial lines, but it has not, heretofore, been position to the initial cutting faces. At any deemed possible to cut a milling cutter to surface back of the initial cutting face and different diameters in accordance with 'a similar to said face, the vsame effective conpredetermined contour and to effect relievtour will be found. Therefore, if the teeth ing movements so that the teeth could be are ground on their front faces to non-raground on the cutting faces Without chan dial helicoids which are the same as the nonlng the effective contour of the* blank. V f radial helicoids of the initial cutting faces, the cltte'r is cut to more than one diameter the effective contour will remain the same. and the teeth have faces which are under- In the accompanying drawings: cut or non-radially arranged, it is essential Figure 1 is a partial front elevational while cutting the blank to compensate the view, partially in section, of a machine conrelieving o eration at the dierent blank structed in accordance with my invention.A diameters or the non-radial cutting faces Fig. 2 is a partial plan view of the maon the teeth. chine showin the tool-carrying slides.

The mechanism disclosed in this appli- Figs. 3 and 4 are detailed views of the cation includes some features of the mamechanism for varying the movement of the chines disclosed in my atents Nos. 1,429, blank-carrying spindle, the views being 611 and 1,429,617, and 1s adapted to cut a taken from Aopposite sides of the machine. cutter such as is described and claimed in Fig. 5 is an end view of the machine taken my copending application, Serial No. 323,- from the left.

110 filed Septemberllth, 1919. Fig. 6 is a transverse vertical sectional Ilhe cutters, which are shaped by the review taken along the line 6-6 of Fig. 1. lieving machine 'disclosed in this applica- Fig. 7 is a vertical longitudinal sectional tion, are adapted to cut any practical conview of the machine. tour. Each cutter blank is cut to different Fig. 8 is a fragmentary plan view showdiameters and is adapted to cut either a recin certain parts of the tool-carrying slides. tilinear or non-rectilinear contour. The cut- -Fig 9 is a transverse vertical sectional ting teeth on the blank are either helical-or view taken along the lines 9 9 of Figs. 1, straight in form and are provided with non- 2 and 7. l radially arranged cuttin faces. In case Fig. 10 is a transverse vertical sectional orm., the Ycutting view taken along the lines 10-10 of..Figs.

. 1, 2 and 7.

Fig. 11 is a fragmentary longitudinal sectional view along the lines 11-11 of Figs. 2 and 9.

Fi 12 is a fragmentary transverse sectiona view taken along the lines 12-12 of face of each tooth conforms ,to a helicoi The helicoid is formed by a generatrix followin a helix on a small cylinder concentric with the Jaxis of the cutter and also following a helix on a much lar r cylinder also concentric with the axis. he teeth of the cutter and the cutting faces may be inrespect to Fig. 3.

ig. 13 is a transverse sectional view the axis and the degree of inclination may taken along the lines 13-13 of Figs. 3 and 4. be varied as re uired. Fig. 14 is a fragmentary vertical trans- Each tooth o the cutter is relieved along verse sectional view taken along the lines lines extendin backward and inward from 14-14 of Fig. 1'. the outline o the non-radial cutting face. The relief lines form a continuous surface tional View taken along the lines 15-15 of or continuous surfaces which extend from Fi s. 1 and 9. y y end to end ofthe cutter. The relief lines ig. 16 is a partial rear view, partially in are properly constructed notwithstanding section, of the machine.

y i Figs. 17, 18 and 19 are diagrammatic the outline of the cutter and notwithstandviews illustrating one operation that may be in the variations in an lar ositlons `refollowed in operating on cutters having nonsu ting from the non-ra ial he ical cutting radially arranged cutting faces.

Fig. 15 is a horizontal longitudinal sec- Fig. 20 is affragmentary sectional view Asimilar in part to Fig. 9 but showing an alternate construction ada ted to be used when operating on cutters liaving non-radi ally arranged cutting faces.

ig. 21 1s a development view of the cam member shown in Fig. 20.

Figs. 22, 23 and 24 are diagrammatic views showing the relation .between the former members and the blanks for cutters provided with non-radially arranged cuttin faces.

ig. 425 is a diagrammatic View, in some respects similar to Fig. 17, illustratind another operation that may be follo d in operating on cutters having non-radially arranged cutting faces.

Fig. 26 is a fragmentary view showing an alternate construction of the former member and the former pin adapted to be used for operating on cutters having nonradially arranged cutting faces.

Fig. 27 is an enlarged lan view of the preferred mechanism use when operating on blanks having non-radially arranged cutting faces.

Fig. 28 is a side elevational view, partially in section, of the mechanism shown in Fig. 27.

Fig. 29 is an end elevational view, partially in section, of the mechanism shown in Fig. 27.

Fig. 30 is a diagrammatic view showing the relation of the levers illustrated in Figs. 27, 28 land 29.

Fig, 31 is a diagrammatic view showing in development a cutter having teeth provided with non-radially arranged cutting faces.

Figs. 32 and 33 are detail views of the ad'usting bar.

igs. 34 and 35 are detail views of th'e correctin lever.

Referring to the drawings, a relieving machine is provided with a main frame or bed 1 upon which the other parts of the machine are mounted. A headstock 2 and a tailstock 3 are provided for carrying the blank which is to be operated on. A tool holding-and-operating mechanism 4 is provided, as'shown in Fig. 1. Preferably the headstock 2 and the tailstock 3 are so arranged as to hold the blank a ainst longitudlnal movement, the tool mec anism 4 being moved longitudinally along the blank in the manner to be presently set forth. When the machine is so constructed, the headstock 2 is fixedly secured to the bed, preferably being formed in part integrallv therewith, as shown. The tailstock 3 is adjustable along the bed j to accommodate blanks or blank arbors of different lengths.

The headstock 2 is provided with a rotatable spindle 5 mounted in suitable bearings 6 and 7, Secured to the spindle in any suitable manner, is a collet chuck 8 form and which is a apted to grip either'.

the yshank of the tool to be formed and reieved or an arbor upon which the tool is mounted. As illustrated, there is a blank A mounted u on an arbor B, the arbor be-l ing enga by the chuck 8. A drive mechanism, inc uding a driving member in the form of a worm wheel 9, which meshes with a Worm 10 on a transverse rotatable shaft 11, is provided for rotating` the spindle 5.

The tailstock 3 may be of any usual or preferred construction, and is, adjustable along ways 12 and 13. The tailstock 3 can be secured in adjusted position by means of a clamp 14 which is controlled by a lever 15. The tailstock spindle 16, which carries a center 17, can be moved longitudinally by means of a screw 18 underthe control of a hand wheel 19. A handle 20 is provided for clamping the 'sleme in adjusted position. As shown in Fig. 2, the center 17 is adjusted into engagement with the end of the arbor B.

The tool mechanism 4 includes a carriage 21 which is longitudinally movable along ways 22 and 23 on the bed 1. A slide 24, which is mounted for transverse movement with respect to the carriage 21, carries the Vcutting tool. In' the figures of the drawings I have shown a non-rotary lathe tool 25, and

such a tool is' preferable for many classes of The diameter may vary uniform from end to end of the blank, thus provi( ing a uni4 form taper, or it may vary in any desired Way so as to provide the blank with any predetermined contour differing from a straight line. The variations in the diameter of the blank are determined by moving the slide 24 together with the tool transversely, and preferably, for regulating and controlling the transverse movements, I provide a former and a former pin, one carried in fixed position on the bed 1, and the other carried by the slide 24. As illustrated, a former 26 is carried bv the bed 1 and a former pin 27 is carried by the slide 24. The former 26 has exactly the same contour with which the blank is to be formed and the former pin 27 has exactl the same shape as the cutting tool 25. 'libe pin is detachably secured to the slide in a manner to` be 'hereinafter set forth, so that it can be removed and another pin be substituted cordiameter.

1anr

responding to a tool dillering in shape from the tool 25 which is shown. A bracket 28, which is rigidly secured to the bed 1, is provided for supporting the former 26. ln order to permit adjustment, the former 26 is secured to a slide 29 which is longitudinally movable along a suitable guideway 3() on the bracket, a screw 31 being provided for effecting longitudinal movement. The slide can be locked in ad]usted position by means of screws 32, 32 which en age a gib 33. The slide. 29 is )rovided wit i a T-slot 34. which is adapted to receive T-bolts passing through the former. Such arrangement is provided to permit the ready adjustment of the former. To further assist iii holding the former in place and to prevent any possible free movement thereof, a hooked bolt 36 is provided which, when tightened, serves to draw` the former back against alsiiitable shoulder on the slide. In practice, a former 26 is selected having the contour with which the blank A is to be formed and then by means of the slide 2!) the former is adjusted longitudinally until it bears the same relation to the forinei' pin 27 that the blank A bears to the tool 25. As the carriage 21 is moved longitudinally the slide 24 with the tool 25 is moved transversely so as to keep the former pin 27 in engagement with the former 26.

In order that the tool may be given a relieving movement to properly reli'e've the several teeth on the blank, it is not rigidly secured to the slide 24 but is transversely movable thereon. A slide 37, which is transversely movable along a suitable guideway, is mounted on the slide 24. A mechanism, for effecting regular reciprocating relieving movements of the slide 37 and the tool in suitable timed relation with the rotative movement ofthe blank, is carried in part by the slide 24. In order that the tool may be adj-usted for blanks of different sizes, a tool-carrying slide 38 is provided which is transversely movable on the slide 37. A screw 39` which is rotated by means of a hand wheel 40, is provided for moving the slide 38. The slide 38 is provided with a transverse T-slot 41 and a tool post 42 is held in place by means of T-bolts 43 entering the slot 41. The tool post has a tool-receiving aperture provided with a. horizontal top wall 44 exactly at the level of the axis of the blank. `The tool 25 is positioned with its top surface engaging the horizontal wall 44 of the tool ost and is held in this position by means o a wedge 45.

It will be observed that, witlr the construction described, the tool is maintained in arallelism as it moves longitudinally for eeding or inward and outward to follow4 the contour.l

The relieving mechanism for moving the slide 37 together with the tool 25 includes a shaft rotatable relieving cani 46 which is mounted on the slide 24 so as to be bodily movable therewith. As shown, the cam is mounted on a longitudinal rotatable shaft 47 which is mounted in bearings 48 and 49 on a bracket 50 depending from the front of the slide 24. A lever 51 is pivoted between its ends on the slide 24 and at its lower end is provided with a roller engaging the cam 46. 'llie upper end of the lever engages an abutment 52 on the slide 37. A coil spring 53 is interposed between the slide 37 and the slide 24, this spring tending to press the slide 37 forward, thus holding the abutment 52 1n firm contact with the upper end of the lever 51. It will be seen that, when the cam 46 is rotated,tlie lever .51 will be oscillated, thiis giving a reciprocating movement to the slide 37 and to the tool 25. -Tlie shape ot' the cani 46 is such that the slide 37 is moved forward relatively slowly at a uniform rate so that the tool n- .y eil'ect a relieving cut, and is then drawn back relatively rapidly so as to withdraw the tool and position it for another eut.

The cam 46 is driven in timed relation with the blank rotation, as before stated. For rotating the cam, I make use of the aforesaid transverse shaft 11. A shaft 54, which is mounted partly in the main frame 1 and partly in a bracket 55 secured thereto, is positioned immediately below the shaft 11. The two shafts l1 and 54 are connected by means of a gear wheel 56 0n the shaft .11, a gear wheel 57 on the shaft 54 and an idler gear wheel 58 meshing with the two gear wheels 56 and 57. The idler gear wheel is mounted on a bearing stud 59 which is earried by an adjustable slotted arm 60. The arm 60 is carried by a hub 61 which assists in supporting the shaft 11. The speed ratio between the two shafts 11 and 54 can be changed by removing one or both of the gear wheels 56 and 57 and substituting other gear wheels of different diameters, it bein clear that the idler gear wheel 58 can be a justed to mesh with such diii'erently diametered gear wheels. A vertical shaft 62 is mounted in the bracket 55 and is driven from the shaft 54 by means of bevel caring `t 3. The shaft 62A serves to drive a llongitudinally splined shaft 65 by means of bevel gearing 64. The shaft is supported partly in a bearing 66 secured to the bed and-partly in bearings 67 on a depending bracket 68 secured to the carria e 21.

worm 69, which is mounted on the 65 between the bearings 67, is splined to the shaft. The worm 69 meshes with a vorm wheel.70 which is connected with-a transverse shaft 71. The worm wheelA70 and the shaft 71 are rotatably mounted in a bearing 72 formed in the bracket 68, and in a bearing 73 formed on a supplemental bra t'ket 74 secured to the bracket 68. A bevel tool.

gear wheel 75 is slidably mounted on the shaft 71 and is engagedby a bearing 76 on the aforesaid bracket 50 dependin from the front end of the slide 24. The bevel gear wheel 75 meshes with a bevel gear wheel 77 on the shaft 47. The bevel gear wheel 75 and the shaft 71 are splined or otherwise suitably constructed so that the bevel lgear wheel is rotated, but is at the same time free to move transversely of the machine when the slide 24 is moved. Inasmuch as the bevel gear wheels 75 and 77 are both supported by the bracket 50, they are at all times held in mesh, It will be seen that with this construction power is transmitted from the shaft 11, through the several parts that have been described, to the shaft 65, and is transmitted from the shaft to the shaft 47 and the cam 46, the connection between the shaft 65 and the shaft 47 being such that free transverse movements of the cam and associated parts is permitted. The cam 46 is given one complete rotation for each tooth of the blank. The machine can be adjusted for blanks with different numbers of teeth by changing the gear wheels 56 and 57, as already explained.

As has already been stated. the machine is adapted for cutting blanks having helical teeth. In order that blanks with such teeth may be properly relieved, it is necessary to effect the relieving movements of the tool in peculiar relation to the rotative movement of the blank so that the relief may be in conformity with the helical teeth. I have stated that the relieving movements of the tool are eHected in timed relation to the rotative movement of the blank; and, for any given position of the carriage., this timed relation is fixed and definite, but when the carriage is moved to bring the tool into a new cutting position, it is necessary to vary the relation between the relieving movements of the tool and the rotative movement of the blank. For this purpose I make use of a mechanism which is in many respects Similar to that set forth in my `aforesaid Patent No. 1,429,611. The )resent construction differs, however, in tiat I have so arranged the mechanism that the aforesaid relationship is varied by changing the rotative movement of the blank rather than by changing` the relieving movements of the While I prefer to change the blank rotation, it will be understood that my present inventionV in its broader aspects is not limited in this respect.

In theV construction illustrated. the driving member or worm wheel 9 is not connected directly with they spindle 5 but is connected indirectly by means of suitable gearing 78 which can be Vsupplementally moved to change the spindle rotation. By preference, this gearing is bodily rotatable and includes a rack and pinion, the rackI being longitudinally slidable in accordance with the longitudinal movements of the carriage 21. A sleeve 79 is coaxially mounted with the spindle 5 and is supported by bearings 80 and 81 in the headstock. The inner end of the sleeve 79 preferably extends into and has a bearing in the outer end of the spindle 5. A frame 82 is recessed to receive t 1e outer end of the spindle 5 and to engage the outer surface thereof. The aforesaid worm wheel 9 is rigidly secured tothe sleeve T9. A shaft 83 having rack teeth formed thereon at 84 is slidably mounted in the sleeve 79. The shaft 83 is splined to the sleeve 79 so as to be rotatable therewith. A transverse shaft 85, which is provided with teeth 86 meshing with the rack teeth 84, is rotatably mounted in bearings in the frame 82. -A transverse shaft 87 is also rotatably mounted in the frame 82. The two shafts 85 and 87 are connected by spur gear wheels 88 and 89. A third rotatable shaft 90 is rotatably mounted in the frame 82. A worm 91, which meshes with worm teeth 92 formed in the periphery of the spindle 5 near the end thereof, is secured to the sha ft 90. A gearing is provided at the side of the bracket 82 opposite from the gears 88 and 89 for connecting the shafts 87 and 90. A ,ear wheel 93 is mounted on the shaft Y87, and a gear wheel 94 is mounted on the shaft 90. An adjustable slotted bracket 95 is mounted on the frame 82 and this carries adjustable bearingr studs 96 and 97 on which are mounted. respectively, idler gear wheels 98 and 99.

An annularly grooved collar 100 is carried by the shaft 83 near the outer end thereof. A longitudinal guide stud 101 is rigidly secured to themain frame l adjacent the shaft 83. A bracket 102 having a fork 103 enteringr the groovein the collar 100 is slidably mounted on the stud 101. The bracket'102 is apertured to receive a longitudinal rod 104, which is connected at its right-hand end with the carriage 21. may be clamped to the rod 104 in any desired relative position and preferably by means of sclews 105. 105 provided with handles 106.

It will be seen that., when the carriage 21 is moved longitudinally along the bed, thc rod 104, together with the bracket 102, will be moved at the same time and to the same extent. By reason of the engagement of the fork 103 with the collar 100 the shaft 83 is similarly moved, thus moving the rack teeth 84. When the rack slides longitudinally the pinion 86 is turned and this serves, by means of the gearing and-the several shafts that have been described, to turn the worm 91. The rotative movement of the worm 91 serves to turn the spindle 5 relatively to the frame 82 and the sleeve 79. It will be understood, as before stated, that the entire gearing 78 rotates bodily with The` bracket 102 the spindle 79. It will therefore be clear that the relative movement of the spindle 5 with respect to the sleeve 79 simply serves to either increase or decrease the spindle rotation to a certain extent. However, the relative movement of the spindle 5 is determined by the longitudinal movement of the rack 84, which in turn is determined by the longitudinal movement-of the cai'- riage 21 and ofthe cutting tool 25 carried thereby. Inasmuch as the relieving cam 46 reciprocates the tool with a` frequency which is normally uniform, and inasmuch as the spindle 5 and the blank are given a changed rotation which is in exact proportion to the longitudinal movement of the carriage and the tool, it lis clear that the relieving movements are effected in such -relation to the blank as to be in conformity with helical teeth.

The amount of variation of the spindle 5 and blank rotation can be changed 1n accordance with the degree of inclination of the helical teeth by removing one or the other 'or both of the gear wheels 93 andV 94 and substituting other gear wheels of different diameters. The idler gear wheels` 98 and 99 can be properly adjusted to inesh with such differently diametered gear Wheels. It is also ssible to cause the relative movements of t e Spindle 5 to take place in either direction in conformity with helical teeth inclined in either direction. As illustrated, the machine is adjusted for cutting teeth with left-hand hellces. For cutting teeth with right-hand helices the idler gear wheel 98 is removed and the gear wheel 99 is adjusted to mesh directly with the gear wheels 93 and 94. When it is desired to cut a blank with straight teeth instead of helical teeth, the gearing is rendered ineffective, as for instance by loosening the clamping screws 105, thus permitting t e rod 104 to slide freely through the bracket 102. By loosening the clamping screws 105 it is possible to preliminarily adjust the carria without affecting the position of the spindle 5 and blank.

When the cutter and the blank have been properly adjusted relatively, the hand-les 106 are turned to connect the carriage with tliemechanism for controlling the spindle rotation.

From the foregoing description it will be observed that in following helical teeth as described, the blank is rotated in each instance through a little more or a little less than one revolution, as required for righthand or left-hand helices. It will further be seen that duringeach rotative movement of the spindle 5 and blank a whole number of relieving movements are effected.

The blank A, shown in Fig. 9, is provided with teeth having their front cutting faces arranged exactly radially. Frequently,

however, it is desired to provide a cutter with undercut or hooked teeth; that is, teeth having their front cutting faces inclined with respect to radial lines. Such a cutter is set forth in my oopending application for milling cutters, Serial No. 323,- 110, filed Se teinber 11th, 1919. For cutting a blank with' undercut faces, it is necessary to vary the ordinary relation between the relieving movements of the tool and the rotative movement of the blank as the cutting tool moves inward or outward to conform to different blank diameters. When such blanks are to be cut, the mechanism heretofore described may be somewhat modified.

One way of varying the relation will be understood by reference to the diagrammatic Fig. ll17. In this view t may be oonsidered to be a fragmentary sectional view taken at the maximum radius r of a cutter C having undercut faces. Under 'the control of the former and the former pin, the cutting tool25 is at a distance r from the blank axis and is in position to engage the point of the tooth shown and to cut the properrelief 'line d-d thereon. The tooth sec tion ata smaller radius 1" is shown at t'. For this radius, without special provision being made, the tool 25 would be in the position indicated by dotted lines at the distance r' from the blank axis. However, by reason of the inclined cutting face on the blank, the blank tooth would not be in engagement with the tool but would be separated therefrom by the angle m. The tool, however, would immediately start 'its inw-ard relieving movement notwithstanding the fact that the blank tooth had not yet reachedit, and the result would be the cutting of an incorrect relief line iV-fl. For a still smaller radius r of the blank, as shown at t", the result would be similar except that the point of the tooth would be Separated from the tool by a greater angle/1n". with the result that the incorrect relief line (2-af would be further from the correct relief line dd.

In order to avoid the errors which would occur, as shown in Fig. 17, I vary the relationship between the relieving movements of the tool and the rotative movement of the blank in such a way that the tool. as concerns its relieving movements, is always in the same position when engaged by the front edge of the tooth. This will be clear from an inspection of Figs. 18 and 19. Fig. 18 shows the tool at the same radius r from the blank axis as was shown in Fig. 17, but the relation of the relieving movement has been so changed that the blank is in position to he engaged by the point of the tool when the relieving movement starts. The tooth is therefore cut `with the correct relief line d-rL Similarly, in Fig. 19, the tool is shown at the same distance r" from the blank axis as was shown in Fig. 17, but

i clined cam grooves.

.movement to conform to he the relation of the relieving movement has been so changed that the blank is in position to be engaged by the point of the tool when the effective relieving movement starts. The tooth is therefore cut with the correct relief line d-d. It will be seen that the operation, as illustrated in Figs. 17 to 19, is in no way effected by or dependent on the longitudinal inclination of the cuttin faces. In other Words, it is immateria whether the cutting faces be helical or straight.

The.required variations in the relationship between the relieving movements of the tool and the rotative movement of the blank can be brought about #either by changing (usually advancing) the blank movement or by changing (usuall retarding) the tool movements. I have ound it simpler, to retard the tool movements, and this is particularly desirable when means are provided as herein disclosed for changing the blank ical teeth. In order that the tool movements may be properly retarded, use may be made of an. alternate construction such as shown in Figs. 20 and 21. This is similar tothat already described except that a shaft 71a and the bevel gear wheel 75a are substituted for the shaft 71'and the gear Wheel 75 before described. yThe shaft 71, instead of being provided with straight splines, is provided with inclined cam grooves 71', and the bevel gear wheel 75l is provided with pins 75. adapted to enter the said grooves. F ig. 21 is a development of the shaft 71a showing the in- W'ith the pins 71 in the full line position shown, which correspends to the radius r, the cam 46 is in position to immediately start the inward relieving movement of the tool. From the descriptlon which has been given of the mechanism for driving the relieving cam, it will be recalled that for any given longitudinal position of the tool, the cam is ordinarily rotated at a speed exactly in yproportion to the rotative movement of the spindle and blank. When the tool is moved inward to a position corresponding tothe radius r', the normal rotative movement of the cam is retarded by an angular distance n which f ,corresponds to the angle m shown in Fig.

hen the tool moves still further in, Ward to a position corres onding to the radius r", the cam is still urther retarded through an angular distance n corresponding to the angle m shown in'Fig. 17. The

'result of this retarding of the tool is Ato cause it tobe always inthe same position as concerns itsv relieving movements when thevfront edge of the tooth reaches it.

The fact that the blank may not have the f maximum radius r is immaterial provided that the bevel gear Wheel 75 is made to take the proper` positions along the cam us at the distance r from the center line of` the bolts. If a cutter E is to be made having a maximum radius 1"', then the former 26 is made with its point of maximum radius at the distance r from the center line of the bolts. The construction of the formers in the Way described insures the location of the sliding gear wheel 75 on the shaft 7ll1 at positions corresponding exactly to the different radii of the blanks.-

Another way of varying the relation between the relieving movements of the tool and the rotative movement 0f the blank to conform to undercut cutting faces, will be understood by reference to the diagrammatic Fig. 25. In this view t, t and t may be considered to be fragmentar sectional views of a cutter C having un ercut faces, the views being taken at the 'radii r. 1" and 7' respectively, as in Fig. 17. In lieu of the former 26 ordinarly used,.there is provided a special former 26'. This former 265, instead of being provided with a vertical guide surface, is provided with a surface of revolution constructed about the center S and having the desiredy contour at any axial pla-ne. The surface of revolution is such that the several radii thereof are the same as tqhe corresponding radii of the cutter C to be formed. The former 26E' is provided with an undercut surface 26, which is at the same angle as the undercut tooth facesof the cutter (j. Cooperating with the former 26 is a. former pin 27E of special form. At any horizontal plane the former pin 27S has the same cross sectional shape as the tool 25, but the former pin is curved rearward at points above the center S of the former.

Under the control of the former 26 and the former pin 27a the cutting tool 25 is held at a distance 'r from the center of the cutter C when the vertical part of the former pin 27 is at a distance r from the center S of the former. For a smaller radius such as 1", without special provision being made, the tool 25 would be in a position at the radius r from the blank. Thetool would immediately start its inward relieving movement notwithstanding the fact that the blank tooth had not yet reached it, and the result would be the cutting of an incorrect relief line, as alread full explained in connection with Fig. 1 W en using the construction illusl trated in Figs. 20 and 21, this error is avoided by retarding the relieving movement of the tool. In accordance with the different operation now to be described, the relieving movement of the tool is not changed as to time but is changed as to position; that is, the tool 25, instead of being allowed to take a position at the radius r from the center, is caused to take a osition at a radius which is reater by the distance s. The dist-ance s is such that the inward relieving movement of the tool, which starts immediately, will enable the tool to properly engage the tooth section t and properl cut t-hedesired relief= thereon. The tool 25 1s held at the increased radius r+s because of the peculiar curved shape of the former pin 27B at-its upper art. The former pin engages the edge o the former at a point along the inclined surface 261, the point of engagement bein at a higher elevation because of the incllnation. The curvature is such that the vertical part of the pin is held at a distance rl-s from the center S of theformer. Similarly, for

the radius 1f," the tool 25, instead of being,

allowed to take a position at the radius r" from the center, is caused to take a position at a radius which is greater by the distance s". The distance s issuch that the inward relieving movement of the tool which starts immediately, will enable the tool to engage the tooth section t" and properly cut the desired relief thereon. The increased radius r-|s is obtained by reason of the aforesaid curvature of the upper part of the former pin 27 E. This curved part of the pin engages the former 26S at another point along the surface 262 this point being nearer the center and therefore at a still higher elevation.

A former such as 26s illustrated diagrammaticall in Fig. 25 would not be entirely practica for the reason that the upper part of the former .pin would interfere with the former at places above the inclined surface 26. A simpler and more practical former is shown in Fig. 26, this being marked 26". It will be seen that this is the same in principle as the former 26 but that the body of the former is below the surface26t instead of above it. This eliminates any interference with the curved part of the former pin 27". The diagrammatic former 26l is shown as having a radius equal to or exceeding the radius of the largest cutter which the -machine is capable of cutting. The former 26" as usually constructed, therefore, has a smaller radius such as 1". p

Referring to Figs. 2, 9 and 10 and particularly to Figs. 27,-28, 29, 30, 31, 32, 33, 34 and.

35, another manner of compensating the relieving o eration at different blank 1ameters for t e undercut teeth or non-radial cutting faces on the blank will be described.

The compensating mechanism disclosed in Figs. 27 to 35, inclusive, is specificall claimed in the joint application of Frie erich Mller and Ernest Wildhaber, Serial No. 469,792, filed May 16, 1921. The former pin 27 is preferably dove-tailed to a sliding bar 107 and is firmly connected thereto by means of a bolt 108. The bar 107 is slidably mounted in an upstanding extending portion 109 from the slide 24 and an arm 110 which is attached to the portion 109. The arm 110 is shown attached to the extension 109 by means of bolts 111, but if so desired such arm may be made an integral art et the slide 24. The bar 107, which sli es in a slot formed in the extension 109 and the arm 110, is provided with shoulder portions 112 which are engaged by plates 113. The plates 113 are attached to the arm 110, in any suitable manner, as by means of screws 114 and. hold the bar 107 in position.

Casings 115 each carrying a roller 116 are mounted on the extension 109 adjacent to the bar 107. The rollers 116 engage guideways on projecting portions 117 from the carriage 21. Reference maybe had `in my copending application Serial No. 522, 304 filed Dec. 14,v 1921, for a complete description of the construction and operation of the rollers 116 and the parts enclosed by the casings 115.

A bracket 118 is mounted on one of the projecting portions 117 of the carriage 21 and is connected thereto by bolts 119. The bracket 118 carries a supporting arm 120 which in turn pivotally supports an L- shaped guide lever or member'121. The supporting arm 120 is provided with a block portion 122 which slides in a suitable guide- Way formed in the bracket 118. A screw 123, which is attached to the block portion 122, 'is provided for adjusting the position of the bar 107 and the former pin 27 in accordance with the maximum diameterof the blank for a purpose to be hereinafter set forth. A gib member 124, which is held in position by set screws 125, is provided for holding the arm 120 in any set position. The. screw 12.3 is rotatably mounted in a plate 126 which is attached to the bracket 118 by means of screws 127. A collar 128, which is an integral part of the screw 123, is disposed on one side of the plate 126 and a removable collar 129 is attached to the screw 123 by a pin 130 on the opposite side is fitted to an opening in the arm 120 and a nut 136 is provided t'or holding the arm 120 and the level' 121 together. A portion 137.l having a center point marked thereon, extends through the nut 136 to serve as a reference point when setting the former in 27 for different blanks provided with di erent undercut. y

A. screw, 138, which is threadedly connected to the connecting lever 131, serves to effect relative movement between the guide member 121 and the arm 120 which supports the guide member.` The screw 138 is rotatably mounted in a lug 139 projecting from the lever 1.21. A fixed collar on the screw is disposed on one side ofthe lug and a removable collar is mounted on the screw 'on the opposite side thereof in order to prevent longitudinal movement ofthe screw. A set screw 140 is provided for holding lthe screw 138 in any adjusted position. A pin 141, having a center point marked therein, is mounted in the lug 139 and together with the portion 137 of the lever 131 serve as reference points for adjusting the lever121.

A second slot 142. which is preferably disposed perpendicnlarlv to the slot 133, is formed in the lever 121. A correcting lever 143 is provided with an elongated portion 144 which is fitted to the slot 142. A

pin 145, which is attached to the bar 107,

extends through the portion 144 of the lever 143 and is provided with a center point marked therein to serve as a reference point when adjusting the screw 123. The lever 143 is connected by a pin 146 to a block 147 which slides in a slot formed in the arm 110.

In the Vmechanism disclosed in Figs. 27, 28, 29, 32, 33. 34 and 35, the center marks on the pin 145 and the connecting lever 131 are adj-usted, by the screw 123, a distance apart which is equal to the maximum radius of the blank. rl`he pin 145 and the correction lever 143, which are mounted upon the slide 24, effect no translatory movement during such operation. The connecting lever 131, which carries the guide lever 121` is moved relatively to the slide 24. The center marks on the pin 141 and on the connecting lever 131 are moved a distance apart by the screw 133 in accordance with the undercut on the teeth of the blank and the angle of relief for the teeth. lVhen adjusting the relative position of the pin 141 and connecting lever 131, it should be noted that the lever 131 is held against transverse movement by the arm 120 which is supported on the carriage 21. Consequently. the guide lever 121 is given a movement of rotation. Thus. the slot 142 is placed at an angle to the center line of the bar 107 and such angle is varied in accordance with the undercut and the angle of relief.

Preferably the screw member 133 v is adjusted prior to adjusting the screw member 123.

The elongated ortion 144 of the Vcorrection lever 143, which is fitted to the slot 142 in the guide lever 121, compels the conrection lever 143 to move an an ular distance in accordance With the angu ar movement of the guide lever. Consequently, when the slot 142 is angularly moved with reference to the center line of the bar 107, the correction lever 143 effects an angular movement, and, in so doing not only moves the block 147 in the slot formed in the arm 110 but also moves the bar 107 and the former pin 21 forward a small amount. It should be noted that, when the guide lever 121 is given a movement of rotation, the only oint on the center line of the slot 142, Whic coincides with the center line of the bar 107, is the center of the pin 145. Consequently, when the slide 24 is moved forward to out smaller diameters on the blank, the correction lever 143 is moved forward to increase the angular position of the slot 142 relative to the center line of the bar 107. The arm 120, which supports the guide lever 121, is as before stated. mounted on the carriage 21 and consequently prevents the guide lever 121 from effecting any movement of translation during the4 forward movement of the slide 24. Thus, the forward movement of the correction lever 143 in the slot 142 compels the guide lever 121 to effect a movement of rotation about the part 135 of the connecting lever 131. The correction lever 143 is compelled to effect an angular movement in accordance with the angular movement of the guide lever. Such angular movement of the correction lever 143 effects a small translator movement of the bar 107 and the former pin 27 relative to the slide 24.

In the above manner, the distance between the tool and the former pin is varied to compensate at different blank diameters for thc non-radial cutting faces on the teeth. The means for determining the distance apart to set the center marks on the pin 141 and the connecting lever 131 will be disclosed more fully when reference is made to Figs. 30 and 31 of the drawings.

In considering the various means for varying the relieving operation at different blank diameters to compensate for the nonradial cutting faces on the teeth of the blank` it should be noted that either the position of the relieving movement mayl be varied or the relieving movement itselfmay be varied. In the means disclosed in Figs. and 21 of the drawings, the relieving movement itself is varied to compensate for the undercut or non-radial cutting faces on the teeth of the blank. In the means disclosed in Figs. and 26 and also in the means disclosed in Figs. 27, 28, 29, 32, 33,

34 and 35, the sition of the relievin Inove ment is varie to compensate for t e nonradially arranged cutting faces. The adjusting mechanism disclosed in Figs. 27, 28, 29, 32, 33, 34 and 35 for varying the relation between the cutting tool and the former in is set in accordance with the maximum diameter of the cutter blank, the amount of relief and the amount of undercut on the teeth of the blank. The screw 123 is adjusted .to make the distance between the center marks on the pin 145 and the connectin lever 131 equal to the maximum radius ofg the cutter blank. The-distance between the center marks on the pins 145 and 146 is made e ial to one unit of length, preferably one intih The distance between the center marks on the in 141 and connectin lever 131 is obtained) mathematicall by a ormula to be explained in describing "gs, 30 and 31. The distance between the center marks on the pin 141 and connecting lever 131, when the slot 142 is arallel to the bar 107, is varied a distance to comensate the relieving operation at different Elank diameters in accordance with the undercut or the non-radial cutting faces on the teeth of the blank.

Referring to Figs. 30 and 31, it is assumed:

al1-The change in distance between the former pin andthe cutting tool.

ezLength of the correction lever 143 (one unit of length).

F=Correction factor for setting compensating mechanism.

g/:Required change in position of relieving movement.

rzRadius of the cutter blank at any point.

F=Total relief including all teeth.

FzThe total undercut.

1i=Maximum radius of cutter blank.

Referring to Fig. 31, the distance y that it is necessary to change the position of the relieving movement for non-radial] arranged cuttin faces is mathematical y determined as fo lows: In Fig. 31 it is assumed l: is the center of the lcutter blank, the line zic is the cutting face of a tooth if the cutting faces were radiallV arranged, and the line zh, is the cutting acc of a tooth if the cuttin faces were non-radially arran ed. The un ercut is assumed to equal F and accordinlgly the line zh, is drawn tangent to the circle aving a radius equal to F. The line gh. is drawn parallel to. and at a distance F from the line ak.

At any point on the cutter having a radius 'r which is less than the maximum radius ro, the angle pkg and q/cl are constructed with the lines pk and g/cequal to the radius r. Comparing a cutter blank having radially arranged cutting faces with a cutter blank having undercut cuttin faces, it is apparent that in the case of un ercut teeth. the cutting tool would approach too near the center k ofthe cutter blank before the cutting faces were reached by reason of the relieving movement. Thus, for a radius' r, the cutting tool would approach the center lc. of the cutter by a distance equal to relief effected through the angle Zkg. Inasmuch as the total relief is F the relieving distance for which compensating must be effected is equal to (angle qkl a distance (angle qlcl 360 when cuttin a point on the cutter blank having a ra ius r.

Referring to Fig. 31:

The angle gclzangle pld-angle pkg.

The angle pkgzangle gica.

It is apparent that the an le pkg equals the angle g/cz when the straig 1t line .eq is assumed to be turned through an angle pkq about the center lc. Upon being turned through such an angle the linezq takes a position coinciding with the line W1. In ike manner the line aq assumes ,a position coinciding with the line gp when rotated through an' angle gkz about the center lc.

herefore angle gbl-:angle pld-angle glue an y: (angle plLggigle p kq) F=| (angle pkl angle glcz) F F F Sine of angle pkl: r?.

i Y. Fl Fl Sine of angle gkz=gk= Inasmuch as theivalue of y, the relieving y `distance for which compensation must be effected, is given in terms of the angle, values must be obtained for angles p/:l and e7/cz.

Therefore y=( le cz-an le gkz)F=2w (arcsin F corresponds to the sine f The angle gi-.l is equal to the arc which corresponds to the known sine of such angle.

Angle pkl=arcsin Y The angle gira is equal to the arc which Angle gkz= l l arcsin The above value of 1/ is the amount the tool must be retarded at any radius r of the cutter blank, when compared with the position of the tool at a radius 7". The retarding amount when compared with a position beyond To is larger. and the retarding amount is largest when the position compared with is considered to extend to infinity. If we consider ro to equal infinity, then arcsin Therefore, if We consider ro to equal ininity the retarding amount y equals F F 2- (arcsm 1r 1' In the case of very small angles, such as are being considered, the arcsin may be taken equal to sine. The solving of the above equation by substituting the sine for the arcsin does not produce an exact mathematical result but an approximation is obtained Which is very much closer to the correct result than can be worked to by modern tools. Accordingly We may use an approximation formula y 1;')i y- 21r 7' for determining the required correction.

It is apparent from the above discussion that the tool must be retarded or compensated an amount which is inversely proportional to the varying radius 7 of the cutter blank. In other words the relieving movement must be retarded an amount which varies inversely with the radius of the cutter blank. Referring to Fig. 3() it is shown that the compensatingr mechanism disclosed in Figs. 27, 28, 29, 32. 33, 34 and 35, satisfies the above requirement and changes the position of the relieving movement inversely in accordancewith the radius of the cutter blank.

The levers, which are shown in Figs. 27, 28, 29, 32, 33, 34 and 35, are diagrammatically illustrated in Fig. 3() in order to more clearly set forth their operative relation to each other. The line af in Fig. 30 is equal to the radius 1' of the cutter blank at anypoint and is the distance between the center marks on the pin 145 and connecting.;r lever 131. The line af is equal in length to e and is placed in the osition assumed by the correction lever 14 for any desired compensation of the relieving operation. The lines ab and fb are respectively drawn perpendicularly and parallelly to the line af. The line fb equals the distance .1'. which represents the variation in distance between the cut-ting tool and the former pin that must be ma e for certain values of the relief, the

undercut and the diameter of the cutter blank. The line b'f' is drawn perpendicularly to the line al1 and has a length F which is to be determined. The line ab is drawn in the angular position necessary to place the slot 142 when a correction .r is made in the distance between the cutting tool and the former pin. Inasmuch as the triangles (lbf and rtfb are right-angle triangies, it is apparent The value of a' thus obtained varies inversely in accordance with the radius fr' of the cutter blank. By taking a' equal to y, a value for the correcting constant F can be The above formula although not absolutely mathematically correct will determine the correction factor F much closer than can be worked to on modern machines.

By means of the equation the correction factor F may be determined inasmuch as e is a constant and the relief F and the undercut VF are known. Upon determining the value of F for a given cutter blank, the screw 138 is operated to adjust the distance between the center-punch marks on the pin 145 and the connecting lever 131 in acordance therewith. The normal dista-nce between the two center-punch marks is diminished in accordance with the value of F. After setting the screw 13B, the screw 1.23 is adjusted in accordance with the maximum radius of the cutter. The screw 123 is so adjusted that the distance between the center-punch marks on the pin 145 and on the connection lever 131 is equal to the maximum radius ofthe cutter blank. The cuttin tool is finally set to cut the maximum rar ius on the cutter blank. Upon movement of the tool to cut a different radius, the position of the relieving movement is varied inversely with the value of o'.

Then the compensating mechanism is set for the maximum radius of the cutter a value of m is indicated on the compensating mechanism inasmuch as the correction is referred to an infinite radius as above set forth. The value of .r thus indicated is engagement with the blank. The correction at any radius r when compared with an infinite radius is FF') i. 2a' 7 The difference in the correction between polnts at radius ro and radius 'r' or the correction at r when compared wlth the radius ro is cll). 21r 1' To It will be seen that two independent variations are effected in the relation between the relieving movements of the tool and the rotative movement of the blank. One of these variations is dependent upon the lon itudinal movements of the tool along t e blank and the other of the variations is dependent upon the inward or outward movement of the tool whereby the blank is out with different diameters. In the preferred embodiment of the invention, as shown and described, the first said variation is effected bv changing the rotative movement of the blank and the second variation is effected by changing the relieving movements of the tool. It will be understood. however, that the invention is not limited to this exact construction, as any mechanism for effecting the required variations in the relationship would be within the scope of the invention.

A screw 150, which en ages a nut 151 carried by a bracket 152 cepending from the carriage, is provided for moving the carriage 21 longitudinally along the hed 1. The screw 15() is supported at its left-hand end in a bearing 153 formed in a bracket 154: secured to the bed. A transverse shaft 155, which is connected with the screw 150 by means of bevel gearing 156. is mounted in the bracket 154. At the front end of the shaft 155 is a hand wheel 157 by means of which the screw 156 may be turned manually to move the carriage 21. In order that the carriage may be moved automatically to feed the tool from one cutting position to another, a suitable mechanism is provided.

This mechanism is preferably adapted to feed the carriage intermittently, but it will be understood that as concerns certain phases of the invention I do not so limit myself inasmuch as the carriage may be removed continuously if desired. Mounted in the bracket 154 is a transverse bearing pin 158 upon which is rotatably mounted a sleeve 159. A gear wheel 160, which meshes with a gear 161 on the shaft 155, is loosely mounted on the sleeve 159 near the inner end thereof. A ratchet wheel 162 is connected to the gear wheel 160. Gear teeth 163, which mesh with a gear wheel 164 secured to the shaft 150, are formed on the sleeve 159 near the outer end thereof. A ratchet wheel 165, which is similar to the ratchet wheel 162, is keyed to the sleeve 15S). A swinging arm 166 is loosely mounted on the hub of the ratchet wheel 165. A link 167, which is adjustably connected at its left-hand end with an oscillating crank arm 168, is pivotallv connected with the arm 166 near the lower end thereof.

The crank arm 168 is secured to a transverse rock shaft 169 which is mounted in a bearing 170 and which carries at its rear end a lever 171. A roller 172, which vis positioned to be engaged by a cam member 173 on a longitudinal rotatable shaft 174, is carried by the lever 171 near the upper end thereof. A transverse pin 175, which carries two similar ratchets 176 and 177 adapted respectively to engage the ratchet wheels 162 and 165, is mounted on the swinging arm 166. Either ratchet can be thrown into or out of engagement with the corresponding wheel. The shaft 17 4 is rotated, in the manner to be presently described, and it will be seen that at each rotation thereof the arm 171 and the crank arm 168 are oscillated. The oscillation of the crank arm 168 is transmitted by means of the link 167 to the plate 166, the extent of oscillation of the plate being adjustable by changing the connection between the link and the crank arm. By means of one or the other of the ratchets 176 or 177, one of the ratchet Wheels 162 or 165 is turned through a small angle, thus turning the shaft 155 and the lead screw 150 and moving the carriage 2l.. It will be seen that the carriage movement:` is relatively great when the pawl 176 is in use, and is relativel small when the pawl 177 is iu use. The desired amount of carriage movement may be obtained by selectingr the proper ratchet and by adjusting the crank arm connection.

Preferably the rotation of the spindle end of the blank is stopped during the feeding movement of the tool. I therefore provide two alternately acting mechanisms` one serving to rotate the spindle and the blank through one revolution, or approximately one revolution, and also serving to effect the relieving movements of the tool` and the other mechanism serving to effect the longitudinal feeding of the tool and preferably also serving to effect other movements to be described.

YThe mechanism for rotating the spindle and the blank has already been described in part, this mechanism including the transverse shaft 11, the worm 10 and the worm wheel 9. The machine is provided with a main power shaft 178, which is adapted to be driven in any suitable way, as for instance. by means of a belt on a pulley 179. A r wheel 180 is rotatably mounted on the shaft 178. The gear wheell 180 is preferably connected to the shaft 178 by means of a splined clutch element 181. The gear wheel 180 meshes with a gear wheel 182 on a longitudinal shaft 183. A long gear wheel 184 is secured to the shaft 183. The gear wheel 184 is surrounded by `a sleeve 185 which is open at the forward upper side. A bushing 186 is slidably and rotatably mounted on the sleeve,185. The bushing 186 is provided with ears between which a gear wheel 187 is rotatably mounted. The

gear wheel 187 meshes wlth the aforesaidrear wheel 184 on the shaft 183. A third llongitudinal shaft 188 is provided, which carries a series of differently diametered gear wheels 189. The shaft 188 is connected with the aforesaid shaft 11 by means of bevel gearing 190. The bushing 186 can be moved angularly and longitudinally on the bushing 185 so as to bring the gear wheel 187 into mesh with any one of the differently diametered gear wheels 189. A spring-pressed plunger 191` which is carried by the sleeve 186. 1s adapted to enter any one of a series of apertures in the sleeve 185 so as to hold the gear wheel 187 in proper position to mesh with any desired one of the gear wheels 189. It will be seen that by this construction the shaft 188 together with the shaft 11 can be driven from the shaft 178 at any one of a series of speeds.

A short. longitudinal shaft 192 is mounted in alignment with the main power shaft 178. The shaft 192 carries a clutch element which is adapted to be engaged by the aforesaid splined clutch element 181 on the shaft 178. 'hen the clutch element is in its right-hand position as viewed in Fig. 16, it drives the gear wheel .180 and the several parts connected therewith. dien the clutch element is in its left-hand position it drives the shaft 192. A transverse shaft 1921 is suitably mounted in bearings in the bed and is connected with the shaft 192 by means of bevel gearingr 194. The shaft 193 carries a worm 195 which meshes with a worm wheel 196 on the aforesaid longitudinal shaft 174.

1n the operation of the machine. it is desirable for the sleeve 79 and .for the shaft 174 to each make one complete revolution alternately in` succession. In order that the desired alternate movements of the sleeve and shaft may take place. I provide automatic mechanism for shifting the clutch element 181. The mechanism used in similar in principle to that shown and described in my Patent No. 1.273.903 for driving mechanism. dated July 30th. .1918. The clutch element 181 is provided with an annular groove into which tit rollers or projections on a forked lever 197. The lever 197 is transversely pivoted on the frame and is provided with a roller 198 by means of which it may be moved. A transverse rock shaft 199 is mounted in the frame above the forked lever 197. The rock shaft 199 carries at its rear end an arm 200 in which is mounted a spring-pressed plunger 201. As shown the` plunger 201 'is V-shaped at its lower end and is adapted to 'engage the roller 198. A lever 202`having upper and lower arms is secured to'the rock shaft 199 at the front end thereof. The upper arm carries a roller 203 which is adapt/ed to be engaged by a cam plate 204 secured to a cam drum 205 mounted on the sleeve 79. The lower arm of the lever 202 carries a roller 206 which is adapted to be engaged by a cam plate 207. The cam plate 207 is secured to a cam drum 208 which is mounted on the shaft 17 4. When the parts are in the positions shown in' Figs. 6, 7 and 16 the 'sleeve 79 is in motion and continues to turn until the cam plate 204 engages the roller 203 and turns the lever `202 in a clockwise direction, as viewed in Fig. 7. or in a counter-clockwise directiom 'as viewed in Fig. 16. Such movement forces the s ring-pressed plunger 201 over the top of te roller 198 and thus tends to swing the lever 197 in the direction to shift the clutch element into position to drive the shaft 192. 1Vhen the shaft 192 is thus driven. the shaft 174 with the cam drum 208 thereon is driven in the direction indicated hy the arrow in Fig. 6. Such movement continues until the cam plate 207 enga s the roller 206 and swings the lever 202 in a counter-clockwise direction` as viewed in Fig. 7 or in a clockwise direction, as viewed in Fig. 16. 1n other words. the cam plate 207 serves to restore the lever to the position which is shown in the drawings. The spring-pressed plun er 201 is again moved over the top of the roller 198 and tends to move the lever 197 inthe direction to move the clutch element 181 into position .to drive the gear wheel 180.

Preferably, I do not depend solely upon the shifting of the lever 202 for thetiming of the movements of the clutch element 181. As illustrated. the lever 197 is provided with opposite fingers 209 and 210 which are adapted to be engaged respectively by latch members 211 and 212. The latch members are held in engagement with the fingers 209 and 210 by means of a spring member 213. Referring to Fig. 16, it will be seen that the latch 211 serves to prevent the movement of the lever 197 toward the left even after the arm 200 has been moved to its right-hand position. Similarly. the latch 212 serves to prevent the movement of the lever 197 toward the right even after the arm 200 has been moved to its left-hand position. A vertieally slidable rod 214, which is normally pressed upward by a spring 215. is provided 

